While it would take a little bit of programming, if you are able to write every frame number output, you can use the explicit offset mode of the RVRetime node.
With the following properties, you can accomplish what I think you are trying to achieve:
You can insert a retiming node in your graph, or if you want to affect it for a single view, you can modify an existing one in the view.
For instance, here’s how you would modify the first source in the current view to have an explicit retiming:
from rv import commands, extra_commands
view = commands.viewNode()
itemToRetime = 0
retimer = extra_commands.nodesInGroupOfType(view, "RVRetime")[itemToRetime]
commands.setIntProperty("%s.explicit.firstOutputFrame" % retimer, )
commands.setIntProperty("%s.explicit.inputFrames" % retimer, [1, 2, 5, 8, 30], True)
commands.setIntProperty("%s.explicit.active" % retimer, )